Alkylation process



Patented Feb. 18, 1947 UNITED STATES PATENT OFFICE ALKYLATION PROCESSWalter A. Schulze, Bartlesville, Okla., and Joseph P. Lyon, Jr.,Phillips, Tex., assignors to Phillips Petroleum Company, a corporationof Delaware Application March 20, 1943, Serial No. 479,932

9 Claim. (Cl. 260-671) alkyl benzenes to give increased yelds ofmonoalkyl benzenes in the process.

It is an object of this invention to provide an improved process for thealkylation of aromatic hydrocarbons with alkylating agents, such asolefins. Another object of this invention is to provide an improvedprocess for the alkylation of benzene with olens in which a novel typeof solid alkylation catalyst is employed. A still further object of thisinvention is to provide an improved process for the synthesis ofalkylbenzenes wherein an eilicient degree of olefin utilization isaccomplished without incurring excessive product losses in the form ofpoly-alkylbenzenes. Yet another object is the improved process for theconversion by poly-alkylbenzenes to mono-alkylbenzenes which consists oftreating the poly-alkylbenzene over solid contact catalysts previouslyemployed in benzene-olefin alkylation step. Further objects andadvantages obtained when employing our improved alkylation process willbe apparent from the disclosure given hereinafter.

The alkylation of aromatic hydrocarbons wherein side chains becomeattached to the aromatic nucleus may be e'ected in the presence of avariety of alkylation catalysts, and with alkylating agents in variousforms such as alkyl halides, alcohols and olefins to give special andvaluable hydrocarbons.

In the alkylation of benzene with olens or compounds yielding oleiins, asuccession of reactions may take place whereby the alkylated productscomprise a mixture of mono, di, tri, and higher alkyl compounds, up tothe limit of substitutable hydrogen atoms of the benzene nucleus.Apparently, the introduction of the original alkyl group activates thenucleus for further substitution, so that the mono-alkylbenzenes aresubject to further alkylation to an extent dependent on the catalyst,the olefin alkylating agent, and the reaction conditions. Since thepoly-alkylbenzenes are often relatively unsatisfactory products forutilization in various processes or compositions, for example, aviationgasoline, their 2 formation represents a loss of valuable raw materialsand decreased yield from the alkylation process.

In our copending application, Serial No.

460,847, led October 5, 1942, now Patent 2,395,-

199, granted February 19, 1946, of which this application is a.continuation-impart, we have described a process for the production ofmonoalkylbenzenes particularly ethylbenzene, wherein the poly-alkylatedproducts resulting from the benzene-olefin condensation are separatedand converted by catalytic cracking into the desired mono-alkylderivatives. In the alkylation step, particularly when employing thelower molecular weight oleflns, e. g. ethylene and propylene, certainsynthetic gel-type solid contact catalysts comprising silica gelactivated with minor proportions of alumina and/or certain other metaloxides are disclosed as particularly effective.

We havenow discovered that when solid contact catalysts, such as thosedescribed above, become spent, that is no longer efficient, for thealkylation reaction, they may be still quite eiective in catalyzing thecracking of said polyalkyl benzenes. Thus, important economies andimproved process efficiency and operation result when the spentcatalysts from the alkylation step are utilized as catalysts in thecatalytic cracking step whereby po1y-alkylated products are converted tothe corresponding mono-alkylbenzenes. In this improved operation, thecatalyst after utilization in alkylating service to a predeterminedlimit of activity or conversion, is next employed as catalyst for thecracking of the heavy alkylate. In this manner, catalyst costs for theprocess are greatly reduced and greater efiiciency in operation may beobtained by use of the same catalyst vessels if desired for bothalkylation and cracking service.

In one speciiic embodiment, the process of the invention comprises thefollowing steps: (l) reacting benzene with an olen in the presence of agel-type silica-alumina catalyst; (2) stripping reaction products fromthe alkylation step to remove unreacted light gases; (3) fractionallydistilling liquid alkylation products to remove unreacted benzene; (4)further fractionating the alkylate to separate mono-alkylbenzene fromhigher-boiling alkylate; (5) treating the higherboiling alkylate atcracking temperatures over the spent alkylation catalyst to obtainpartial conversion to light gases comprising ethylene and a liquidfraction comprising benzene, mono-alkylbenzene and any unconverted heavyalkylate; (6) passing the liquid products from the cracking step intothe stream of liquid products from the alkylation step to recover thealkylbenzene.

While the operation of the process may be considered intwo stages orsteps, the alkylation step and the cracking step, it is to be understoodthat the two steps may preferably comprise a continuous and integratedoperation with the same fractionation equipment being utilized tohandlethe products from both catalytic conversions. The followingdetailed description of the process as applied to the synthesis ofethylbenzene will serve to illustrate the various operations involved.

An ethylene-containing stream, either substantially pure ethylene or aCz hydrocarbon mixture, is admlxed with a stream of benzene in thedesired molar proportions prior to or immediately after entering thecatalyst chamber.' The benzene-ethylene mixture passing through the bedof solid silica-alumina catalyst at proper pressure and temperatureconditions undergoes alkylation producing ethylbenzene and small amountsof diand tri-ethylbenzenes.

The solid adsorbent catalysts which are preferably used as a feature ofthe process are most accurately described as dried gels, characterizedby their method of preparation, physical properties and chemicalcomposition, all of which impart particular catalytic activity.

The preferred catalysts are usually prepared by first forming a hydroussilica gel or jelly from an alkali silicate and an acid, washing solublematerial from the gel, treating or activating the gel with an aqueoussolution of a suitable metal salt, and subsequently washing and dryingthe treated material. In this manner, a part oi the metal, presumably inthe form of a hydrous oxide or hydroxide formed by hydrolysis, isselectively adsorbed by the hydrous silica, and is not removed bysubsequent washing. ,The most often used catalyst of this type. atpresent, is a silicaalumina catalyst, prepared by treating a wet orpartially dried hydrous silica gel with an aluminum salt solution. suchas a solution of aluminum chloride or sulfate, and subsequently washingand drying the treated material. However, catalysts of a similar naturebut differing among them.. selves as to one or more specific properties,may be prepared by using a hydrolyzable salt of a metal usually selectedfrom groups IVA and/or IIIB of the periodic system. As listed in ModernInorganic Chemis by J. W. Mellor (Longmans, Green Co. (1939), Revisedand Edited by G. D. Parkers) on page 118, group IIIB consists of boron,aluminum, gallium, indium, and thallium, and group IVA consists oftitanium, zirconium, hafnium, and thorium. More particularly a salt ofaluminum, gallium, indium or thallium from group IIIB or a salt oftitantium, zirconium or thorium in group IVA may be used to treat silicagel to prepare catalysts of this general type. These catalystcompositions contain a major portion of silica, and minor portion ofpromoting metal oxides, and are sometimes termed silica-alumina typecatalysts. The minor portion of metal oxide, such as alumina, willgenerally not be in excess of 10 per cent by weight, and will moreoften, and generally more preferably, be between about 0.5 and per centby weight.

Modiilcations may be made in the foregoing procedure and catalysts ofsuitable activity may result. One obvious alternative is the addition ofthe metal salt to the silicate before gelation.

This method enables the incorporation of greater proportions of metaloxide, but activity may not be proportional to increasing metal oxidecontents above about 1 to about 15 weight per cent so that little isgained by the modification and the proper degree of salt and acidremoval may be more diiiicult. Non-uniform materials usually result fromthe mechanical mixing of hydrous metal oxide and silica gels, so thatcatalysts prepared in this manner may be less satisfactory. Other meansof accomplishing the preparation may be devised, however, in view of theforegoing description.

Although'the above-described synthetic catalysts are preferred inpracticing our invention, other solid contact catalysts may be utilized,particularly other silica-alumina type catalysts which are prepared fromnaturally-occurring minerals such as zeolites and clays by acidtreatment to remove ferrous impurities and the like and to adjust thesilica-alumina ratio, although such preparations are usually lessactive, particularly in the alwlation step, than the preferred synthetiegels, and require higher cracking temperatures.

The preferred catalysts ofthis invention are of such nature that it ispossible to employ them for long periods under the conditions selectedfor the alkylation reaction with a very gradual decline in activity.When this decline in activity makes continued service for alkylatlonundesirable. the catalyst retains suitable activity for the vcatalyticcracking reaction under conditions which are usually somewhat diiferentfrom those required for alkylation. In many cases the activity and lifeof the catalyst in the catalytic cracking step are relativelyindependent of the length of the' period during which the catalyst wasemployed for alkylation.

In the practice of our invention, the ethylbenzene and heavier alkylateare stripped of the light gases and the alkylate stream may befractionated to recover the benzene which is recycled to the alkylationstep. The light gases may or may not be recycled, depending upon theethylene content. The liquid alkylate. comprising principallyethylbenzene and diethylbenzenes is fractionated to recover theethylbenzene. The heavier alkylate is vaporized and heated to crackingtemperatures. A diluent such as steam, nitrogen, CO2, methane, etc., maybe added before and/or after the heating step. The heated vapors thenpass through a cracking zone 'containing spealkylation catalyst.Products from the cracking zone comprise ethylbenzene, benzene andethylene and light gases. The products are preferably added to thealkylate stream and fractionated in the same equipment and theunconverted heavy alkylate recycled to the catalytic cracking step forfurther conversion to ethylbenzene.

Catalyst life in the alkylation step of the present process isordinarily very long, since the relatively low temperatures andpreferred-liquid phase operation both tend to prevent the accumulationof tarry poisons and carbonaceous deposits. Thus several hundred volumesof alkylate may often be produced per volume of catalyst before anysignificant change in activity is evident. The catalyst is not used inthe alkylation reaction after the conversion declines seriously and/orexcessive temperatures are required to maintain the alkylation rate.However, we have found that the activity of the spent alkylationcatalyst is superior to many other'catalysts for cracking operations inthe second step of the present process. Thus,'when the catabe usedeffectively in the cracking step by operating at usually highertemperatures and other conditions chosen to favor the cracking reaction.

The spent alkylation catalyst may be used in the catalytic cracking stepimmediately after being removed from alkylation service. In a preferredembodiment a suicient number of catalyst chambers is provided to enablecontinuous alkylation while a chamber containing catalyst spent for thealkylation reaction is employed to convert the heavy alkylate previouslyand/or concurrently produced.' In this manner, transferring of thecatalyst may be avoided. Since the volume-of heavy alkylate to behandled is ordinarily relatively small compared to the volume ofmono-alkylate, one catalyst chamber in cracking service may besuflicient to process the heavy alkylate produced in one or morealkylation chambers over a relatively long period. Mobile catalystsystems, such as one employing a moving bed of granular catalyst, or oneemploying powdered catalyst at least partially suspended in reactants,may be used, with suitable modification.

'I'he catalyst to be used in the cracking step is ordinarily put inservice without intermediate treatment and employed as long assatisfactory conversion is obtained. However, it has been noted thatreactivation treatment, such as the burning olf of carbonaceous depositsmay be utilized prior to or after use in the cracking stepwithoutimpairing the activity of the catalyst for the cracking reaction. Theeconomics of such conventional reactivation procedures may depend on therate at which catalyst becomes available from the alkylation step aswell as the length of the period of satisfactory activity in thecracking step. As mentioned above, since the relative volume of heavyalkylate is small, the alkylation step may furnish suiiicient spentcatalyst to supply the requirements of the cracking step. Catalyst whichhas been exposed to high temperatures in the cracking step or insubsequent reactivation is not usually suitable for further service inthe alkylation reaction.

Temperatures for the alkylation step are ordinarily in the range ofG-700 F. with a somewhat narrower range of 450-650 F. ordinarilypreferred for alkylation with ethylene. When higher olefins such aspropylene are utilized, somewhat lower temperatures, e. g., Z50-450 F.are ordinarily preferred. Within these limits, specific temperatureswithin the catalyst bed are .chosen to conform to the catalyst activityand the composition of the feed to give the most efficient conversion atthe operating pressure and moderate flow rates, of about 1 to 5 liquid'volunies of feed per volume of catalyst per hour. In some cases withextremely reactive catalysts, low benzene-olefin mol ratios, and longercontact times, the lower temperatures may be adequate.

Operating pressures used in the alkylation reaction are chosen inaccordance with the reaction requirements but are somewhat dependentupon the temperature. For example, pressures in the range of 100 to 2000p ounds per square inch gage are employed in the alkylation reaction,which is apparently promoted to some extent by pressure. Thus, increasedpressures tend to promote conversion and enable rapid reaction rates atsomewhat lower temperatures and/or shorter contact times.

In the second or catalytic cracking step, temperatures are muchhigherthan those of the corresponding alkylation step, and are usually in therange of about '100 to about 1100 F. Preferred temperatures for thecracking of heavy alkylate from benzene-ethylene alkylation over spentalkylation catalyst are from about 950 to about 1100 F. In the case ofpoly alkylated products from alkylation with higher olens such aspropylene, the preferred cracking tempera.-A tures may range from about700 to about 900 F.

Pressures in the cracking step are usually maintained at low values tofavor the cracking reaction and suppress undesirable side reactions. Inmost cases, low superatmospheric pressures of about zero to about 100pounds gage are satisfactory to sustain the iiow of vapors through thecatalyst chamber and auxiliary equipment.

It is often desirable to include a substantially inert diluent in thefeed to the cracking step to serve as a heat carrier and to suppresscarbon deposition and destructive side reactions. For this purpose steamis ordinarily preferred, although refractory hydrocarbon gases, andother gases such as nitrogen, carbon dioxide, etc. may be utilized.

The feed stocks for the above-described process may be derived from anysuitable source, such as petroleum refining processes which produce botharomatic and olefm hydrocarbons, or from unrelated sources when processeconomics are favorable. We have found the process well adapted forutilizing ethylene from refinery gas streams which ordinarily containvery small amounts of gases other than ethane and ethylene. When usedasa selective chemical synthesis, it is advantageous to employ relativelypure benzene and olefin, or an olefin feed stock containing a singlereactive component such as a mixture with the corresponding parafln. Theuse of relatively pure benzene also results in longer catalyst life andpurer products since the production of compounds of such boiling rangeas to contaminate the alkylate is avoided.

While the foregoing disclosure has been relatively speciflc to theproduction of ethylbenzene from benzene and ethylene, it may be adoptedwith suitable modifications to processes utilizing higher olens whichcan be successfullyl alkylated over solid catalysts of the typedescribed. Thus, the adoption to the production of cumene involves theuse of catalyst spent in the benzenepropylene alkylation tocatalytically crack the heavy alkylate and produce further quantities ofcumene. Furthermore, heavy alkylate resulting from alkylation reactionsin the presence of other types of alkylation catalysts may be treated bythe process along with heavy alkylate produced over the original solidtype catalyst.

These and other modifications will be obvious from the disclosure andthe following examples which illustrate specific applications of theprocess. These examples, however, are not to be construed as unduelimitations upon the scope of the invention.

Example I The catalyst used in the following example was prepared by thesteps of (l) forming silica hydrogel by introducing sodium silicatesolution into excess sulfuric acid: (2) washing and partially drying thegel to a SiOzzHzO m01 ratio between 1:1 and 2:1; (3) activating thepartially dried gel by boiling in a solution of iron-free aluminumsulfate; (4) washing the activated gel to remove free acid and salts,and finally drying to form.

hard, glassy granules. This catalyst was used in 12 to 20 mesh sizes.

A benzene-ethylene feed was'premixed in a molar ratio of 3.7:1 and thismixture passed over the catalyst at 520-570" F. and 1000 pounds gagepressure. The feed rate was `1.5 liquid volumes of charge per volume ofcatalyst per hour.

The products of alkylation` were stripped of light gases and the liquidalkylation products were successively fractionated to remove untreatedbenzene, and to separate ethylbenzene from diethylbenzene and highersubstituted homologs. The alkylate consisted of 84.6 weight per cent ofethylbenzene and 15.4 weight per cent of heavy alkylate, principallydiethylbenzene. The ethylbenzene was recovered substantially pure, andthe heavy alkylate was passed to the catalytic cracking step.

The heavy alkylate charge admixcd with steam in a steam-hydrocarbon molratio of 3.8:1 was passed at 995 F. and 4 pounds gage pressure through acatalyst chamber containing spent catalyst from the alkylation reaction.The hydrocarbon flow rate was i liquid volume per volume of catalyst perhour. The' eiiiuent products were cooled to condense the liquidcomponents and water, with the latter separated prior to fractionation.Light gases containing about 90 mol per cent ethylene were removed fromthe condensed hydrocarbons, and recycled to the alkylation step.

The liquid hydrocarbon products from the cracking step were added to thestream of liquid alkylation reaction products to effect separation intobenzene, ethylbenzene and unconverted diethylbenzene. The per passconversion was 25-30 weight per cent of the heavy alkylate charged andproduct analysisshowed that each 100 mols of converted heavy alkylateproduced about mols of benzene and 85 mols of ethylbenzene.

Example II Silica-alumina catalyst which had been used to alkylatebenzene with propyleneat 350 F. and 400 pounds gage pressure was used ascracking catalyst after production of about 300 volumes of alkylate pervolume of catalyst. The heavy alkylate, principally diisopropylbenzeneproduced in the alkylation was cracked over this catalyst at 750 F. and5 pounds gage pressure, and a charge rate of 2 liquidvolumes per volumeof catalyst per hour. The per pass conversion was about 60 weight percent of the charge and the principal products were propylene, benzeneand cumene.

The accompanying drawing is provided for the purpose of betterillustrating a preferred modification of our invention involving theformation of ethylbenzene, which is a desirable hydrocarbon used, forexample, in the manufacture of styrene by subsequent dehydrogenation.The drawing represents somewhat diagrammatically one preferredarrangement of apparatus which may be used in this process.

In the drawing, a propane-propylene feed is passed via line l0 throughtubes in cracking furnace l2 wherein the propane and propylene arecracked at an average pressure of about 27 pounds gage at about 1450 F.for a total time of about 6 seconds to give good yields of ethylene.Efuents pass via line I4 through a tar remover, air-,iin cooler, andcarbon separator indicated diagrammatically at I6, and then via line I8into a separation system 20, wherein C4 and heavier hydrocarbons areremoved, as by line 22, with lighter 'gases passing on via line 24. Apreferred manner of effecting this separation is by a V3- or 4- stagecompression-scrubbing system, such as -is known to the art, to removearomatic oils, followed by a fractionator to separate Ca and lighteroverhead from remaining C4 and heavier components.

The products from line 24 are refrigerated in zone 26 to a lowtemperature, as by propane and ethylene cooling steps and passed vialine 28 into system 30 for fractionation into methane and small amountsof lighter gases yvhich pass off via line 32, ethylene which is passedvia line 34 to the alkylation step described below, ethane which isremoved from the system via line 36, and propane and propylene which arerecycled via line 38 to line I0 for further cracking.

Ethylene from line 34 (which may of course be obtained or manufacturedin anyv suitable way .which may if desired be dilerent from the crackingmethod shown) is passed via line 40 into admixture with benzene fromline 42, and the resulting mixture passed into preheater 44 wherein itis brought to alkylation temperature. A compression step (not shown) maybe used, generally prior to preheater 44, to ensure substantiallyliquid-phase, or dense-phase, conditions in the alkylation. The benzeneto ethylene mol ratio is preferably substantially above one in thealkylation reaction zone. Hot alkylation feed passes from preheater 44via line 46 and one or more of the valved branches 41, 49, 5|, and 53,into one or more of the catalyst chambers 48, 50, 52, and 54 containingalkylation catalyst of the type hereinbefore described. Alkylationeilluents pass from the catalyst cases via the corresponding valvedlines 56, 58, B0, and 62 into conduit 64 and thence to accumulator 66,wherein small amounts of gas separate and are passed via line 68 back toseparation system 20 in the ethylenemanufacture plant (connection notshown for simplicity in drawing). Liquid from 66 is passed via line 10into fractionator |2, from which substantially pure benzene is separatedoverhead and recycled via line '|4to junction with fresh benzeneentering via line 16 and thence into line 42 to be passed to thealkylation reaction. Material heavier than benzene is passed fromfractionator '|2 via line 18 to fractionator 80. Ethylbenzene isseparated therefrom in line 82 as a product of the process. Smallamounts of heavy refractory material are removed from the system vialine 84.

Polyalkylbenzenes are recovered from fractionator and passed via line 86to preheater 08 wherein they are heated to cracking temperature. Thethus-heated polyalkyl benzenes pass via line and one or more of thevalved branches 92, 94, 96, 98, into one or more of the catalystchambers 46, 50, 52, and 54 containing catalyst which-has becomedeactivated in carrying out the alkylation process. The cracked productscomprising ethylene, benzene, ethylbenzene, and unconverted heavyalkylate then pass into conduit |00 via one or more of the valved lines|02, |04, |06, and |08, and then 'into accumulator H0, usually after awater quench. The vapor phase is passed from unit ||0 via line H2 backto line 40 so that the ethylene is again used in the alkylation step,while the liquid phase is passed from unit ||0 via line I I4 toadmixture with alkylation ellluents in line 84 and on into theseparation system described above. The use of a common separation systemfor both alkylation and cracking eilluents in the manner describedherein is one of the advantageous features of the invention.

While four catalyst chambers have been shown,

it will be evident that a 'greater or smaller number may be provided asdesired. Ordinarily it is -preferred to operate simultaneously at leastone chamber on alkylation, at least one on cracking, and at least oneshut down for catalyst regeneration, or removal and replacement ofcatalyst, repairs, etc. f course, it is generally desirable to limit thesize of a, catalyst chamber so that in a large plant several chambersmay be used at one time for each step in the process. While noregeneration system has been shown in the drawing, its use as describedhereinbefore for effecting regeneration of spent cracking catalyst willbe obvious to one skilled in the art, who may readily supply thenecessary conventional equipment if the supply of spent alkylationcatalyst is not sufcient to provide all the requirements of the crackingstep or if for other reasons regeneration is deemed advantageous.coolers, controls, and other auxiliary equipment may readily be suppliedby one skilled in the art. Various other modifications may of course bemade without departing from the spirit of the invention.

We claim:

1. A process for the synthesis of a mono-alkyl benzene which comprisesreacting benzene with a low-boiling aliphatic olefinin an alkylationstepin the presence of a solid, synthetic silica-alumina, catalyst underalkylating conditions to produce an alkylate which contains a majorproportion of mono-alkyl benzene together with polyalkyl benzenes,fractionating said alkylate to separate mono-alkyl benzene frompoly-alkyl benzenes, treating said poly-alkyl benzenes, as the onlyreactive hydrocarbon material charged, under cracking conditions in thepresence of a catalyst consisting of a solid, synthetic silica-alumina,catalyst which has become substantially spent as an aromatic alkylationcatalyst during use in the aforementioned alkylation step and which isused as a catalyst for said cracking without any intermediate treatment,to convert polyalkyl benzenes to mono-alkyl benzene and lowboilingoleiines, and separating mono-alkyl benzene from the cracked products.

2. A process for the synthesis of ethylbenzene which comprises reactingbenzene with ethylene in the presence of a solid adsorbent alkylationcatalyst, comprising essentially a synthetic silica gel materialactivated with a minor proportion of alumina under alkylating conditionsto produce an alkylate which contains a, major proportion ofethyl-benzene together with poly-ethyl benzenes, fractionating saidalkylate to separate ethylbenzene from poly-ethyl benzenes, treatingsaid polyethyl benzenes, as the only reactive hydrocarbon materialcharged, under cracking conditions over a catalyst consisting of a,solid adsorbent catalyst, comprising essentially a synthetic silica gelmaterial activated with a minor proportion of alumina which haspreviously been used for and has become substantially inactive for saidalkylation and which is used as a catalyst for said cracking without anyintermediate treatment, to convert poly-ethyl benzenes at leastpartially to ethylbenzene and ethylene, and separating ethylbenzene fromthe cracked products.

3. A process as in claim 2 in which products from the cracking step areprocessed to recover ethylene, which is returned to the alkylation step,and a, mixture of benzene, ethylbenzene, and unconverted poly-ethylbenzenes, which mixture is combined with the stream of alkylationproducts prior to separation into the principal components.

Valves, compressors,V

4. A process for producing ethyl benzene from ethylene and benzene,which comprises passing a hydrocarbon mixture comprising ethylene and a.molecular excess of benzene through a bed of granular synthetic gelcatalyst, comprising essentially silica and aluminum oxide and preparedby contacting an acidic hydrous silica gel with an aqueous solution of ahydrolyzable aluminum salt to adsorb said metal as a hydrous oxide tothe extent of about 0.5 to 5 per cent by weight, and subsequentlywashing and drying the said treated gel, maintaining said hydrocarbonmixture under alkylation conditions while in the presence of saidcatalyst, removing from eiiiuents of said alkylation ethyl benzene as aproduct of the process, removing also from said eiiiuents a polyethylbenzene fraction, removing from said alkylation said catalyst when ithas become substantially inactive as a catalyst for said alkylation,passing said polyethyl benzene fraction, as the only reactivehydrocarbon material charged, through a bed of said inactive alkylationcatalyst as the sole catalytic material employed at a temperaturebetween about 700 and 1100* F. and under a low pressure to form ethyleneand ethyl benzene without subjecting said inactive alkylation catalystto any intermediate treatment, and recovering said ethyl benzene as afurther product of the process.

5. The process of claim 4 in which said conversion of polyethyl benzeneto ethyl benzene and ethylene is conducted in the presence of steam.

. 6. A process for producing a monoalkyl beni zene, which comprisesdehydrogenating a lowboiling parain hydrocarbon to produce a lowboilingolen and lighter gases, passing an eluent of said dehydrogenationcontaining said products to a first separating means and separating anolen fraction comprising said olefin from light gases, admixing withsaid olefin fraction an olefin-containing gaseous material ashereinafter recited and a molecular excess of benzene and subjectingsaid mixture to the action of a solid alkylation catalyst, comprisingessentially silica and an oxide of the group consisting of alumina,gallia, india, thallia, titania, zirconia, and thoria and prepared' bycontacting an acidic hydrous silica gel with an aqueous solution of a.hydrolyzable salt of a metal corresponding to said oxide to absorb saidmetal as a hydrous oxide to the extent of about 0.5 to 5 per cent byweight, and subsequently washing and drying said treated gel underalkylation conditions to produce a monoalkyl benzene, polyalkyl benzenesbeing concomitantly produced in minor amounts, passing eiiluents of saidalkylation to a second separating means, separating therefrom at leastone polyalkyl benzene, subjecting said polyalkyl benzene,

as the only reactive hydrocarbon -material charged, to reactionconditions of elevated temperature vand low pressure in the presence ofa solid catalyst, which has previously been used in said alkylation stepand has been transferred directly from said alkylation after it hasbecome substantially inactive for said alkylation, as the sole catalyticmaterial employed` to produce a monoalkyl benzene and a low-boilingolen, separating from eiiiuents of the last .said reaction a gaseousmaterial comprising low-boiling olens so produced and a liquid materialcomprising normally liquid products so produced, and including amonoalkyl benzene product, passing said gaseous material to theaforesaid alkylation step as additional olefin reactant, passing saidliquid material to the aforesaid second separating means,

1l separating also from said second separating means light gases andpassing same to said iirst separating means, and recovering from saidsecond separating means as a product of the process a monoalkyl benzenefraction containing material produced in each said reaction.

7. A process for producing a monoalkyl derivative of an alkylatablearomatic hydrocarbon, which comprises subjecting a hydrocarbon mixturecomprising a low-boiling oleiln hydrocarbon and a. molecular excess ofan alkylatable aromatic hydrocarbon under alkyiating conditions to theaction of a solid synthetic gel catalyst comprising essentially silicaand an oxide of the group consisting of alumina, gallia, india, thallia,titania, zirconia, and thoria. and prepared by contacting an acidichydrous silica gel with an aqueous solution of a. hydrolyzable salt of ametal corresponding to said oxide to adsorb said metal as a hydrousoxide to the extent of about 0.5 to 5 per cent by weight, andsubsequently washing' and drying said treated gel, removing from emuentsof said alkylation a monoalkyl derivative of said aliqlatablehydrocarbon as a product of the process, removing also from saideiiiuents a fraction comprising a polyalkyl derivative of saidallwlatable aromatic hydrocarbon, subjecting said polyaikyl derivativefraction, as the only reactive hydrocarbon material charged, to reactionconditions of elevated temperature and low pressure in the presence of asolid-catalyst which has previously 12 been used in said allryiation andhas been transferred directly from said aikylation after it has becomesubstantially inactive for said alkylation. as the sole catalyticmaterial employed to produce a'monoaikyl derivative of said alkylatablearomatic hydrocarbon 'and a low-boiling olefin and recovering saidmonoalkyl derivative as a further product of the process.

8. lhe process of claim 7 in which said lowboiling olefin is ethylene.

9. The process of claim 7 in which said lowboiling olefin is ethyleneand said alkylatable aromatic hydrocarbon is benzene.

WALTER A. SCHULZE. JOSEPH P. LYON, Jn.

REFERENCES CITED The following references are of record in the file oithis patent:

UNITED STATES PATENTS

